The present invention relates to determining moisture content and uniformity of solid plant matter, and more particularly, to a method for non-invasively determining moisture content and uniformity of solid plant matter during on-line drying or cooling forced-air treatment, based on measuring temperature, humidity, and flow rate of the forced-air passing through the volume of the solid plant matter.
A wide variety of raw materials used for manufacturing food, pharmaceutical, and tobacco products are obtained from solid plant matter. Hereinafter, the term xe2x80x98solid plant matterxe2x80x99 refers to any essentially solid part or component of a plant, including, but not limited to, leaves, beans, seeds, grains, flowers, stems, stalks, and roots, in raw or processed, loose or web, form. For example, tea leaves, coffee beans, and tobacco leaves are used for manufacturing tea, coffee, and tobacco products, respectively.
From the site of cultivation, raw solid plant matter is harvested, bundled or packaged, transported, and stored in a variety of forms before being used in manufacturing processes. Subsequent food, pharmaceutical, and tobacco product manufacturing processes are performed in stages involving a variety of procedures, from initial processing of loose raw solid plant matter leading to using the initially processed solid plant matter for producing bulk quantities of various consumer end products. These end products are subsequently sub-divided, packaged, stored, and transported throughout the consumer marketplace according to distribution, marketing, and selling criteria.
The present invention focuses on that stage of the manufacturing sequence involving in-house treatment of initially processed raw solid plant matter. In particular, the stage involving drying or cooling of wetted raw solid plant matter by subjecting it to an on-line forced-air treatment. As part of an overall manufacturing sequence, some types of raw solid plant matter are intentionally and controllably wetted, for example, by subjecting them to steam, for the purpose of enhancing particular physicochemical properties of the raw solid plant matter needed for entry into further downstream processes. For example, raw tobacco leaves are wetted for causing opening of pores of the leaves, resulting in enhancing particular physicochemical properties of the tobacco leaves essential to characteristics and performance of tobacco end products.
In such a manufacturing sequence, wetted raw solid plant matter exiting a wetting apparatus is transported by an on-line conveyor passing through a drying or cooling apparatus, such as a multiple open sided chamber, featuring an inlet and outlet through which forced-air passes, thereby drying or cooling the wetted solid plant matter. During the drying or cooling forced-air treatment, moisture content, and consequently, uniformity, throughout the volume of the initially wetted solid plant matter change, according to the operating parameters of the forced-air treatment. At this stage of such a manufacturing sequence, moisture content and uniformity are important properties of the solid plant matter which need to be determined, monitored, and controlled prior to the solid plant matter entering further downstream processes or storage. In particular, if the moisture content and/or uniformity of a given wetted solid plant matter raw material are outside of established quality control values, use of such solid plant matter is expected to lead to downstream intermediate products, or stored solid plant matter, similarly failing their established quality control values, potentially causing undesirable rejection of material, manufacturing down time and added cost.
Recently, several methods and devices, based on microwave technology, have been disclosed for on-line non-invasively measuring and calculating moisture content of materials, including plant derived materials such as cotton, tea leaves, and tobacco leaves. Disclosures include U.S. patent application Ser. Nos. 09/143,966; 09/126,384; 08/974,983, and 08/777,872. In these disclosures, typically, a radiation source beam is transmitted through a portion of material and is received by a receiving antenna, which then produces a signal. Microwave signal parameters such as attenuation and phase shift are used to measure and determine moisture content, density, and uniformity of the material. The disclosed methods and devices are primarily applicable to bulk quantities of loose or packaged materials, such as bales, being transported on-line through a silo or being transported between bulk material storage facilities, and include no description relating to measuring or determining moisture content of the material during a drying or cooling process.
In U.S. Pat. No. 5,870,926, there is teaching of applying infrared spectroscopy for non-invasively determining moisture content of solid plant matter during an on-line drying or cooling treatment. In this disclosure, exposed surface area of solid plant matter passing through a drying or cooling apparatus is subjected to an infrared beam, whose output is compared to the output of a reference or calibration beam, for obtaining on-line values of infrared reflections proportional to moisture content of the solid plant matter exiting the drying or cooling apparatus. In practice, the disclosed method and device are significantly limited by interference during the infrared measurements, caused by the presence of varying quantities of dirt on the surface of the infrared source and receiver apparatus, and dust in the surrounding air. This disclosure is additionally limited by the infrared measurements providing information relating only to the exposed surface area of the solid plant matter during on-line transport, and is not capable of providing moisture content or uniformity information relating to the volume of the moving solid plant matter. Even for low density loose solid plant matter, results of moisture content or uniformity obtained by related methods and devices are significantly limited.
Aside from radiation based methods and devices, currently available methods and devices for non-invasively determining moisture content, and consequently, uniformity, of wetted solid plant matter passing through an on-line drying or cooling forced-air treatment are typically based on only measuring the humidity of the forced-air passing through the drying or cooling device. Here, for a given temperature, the difference in humidity of the forced-air entering and exiting the drying or cooling apparatus is proportional to moisture content, and consequently, uniformity, of the solid plant matter exiting the drying or cooling apparatus.
Actually, in an on-line drying or cooling forced-air treatment of wetted solid plant matter, measurement of several operating parameters, in addition to humidity of the forced-air, is required for accurately and reliably determining moisture content and uniformity of the continuously moving solid plant matter. Primary operating parameters most affecting moisture content and uniformity of the moving solid plant matter are the temperature, humidity, and flow rate of the forced-air used for drying or cooling the wetted solid plant matter as it passes through a drying or cooling apparatus. Secondary operating parameters affecting moisture content and uniformity of the moving solid plant matter include (1) the volumetric bulk material transport rate of the solid plant matter transported by an on-line conveyor through the drying or cooling apparatus during the drying or cooling forced-air treatment, where this operating parameter is a function of the configuration or volume of the bulk solid plant matter fed onto, and situated on, the on-line conveyor, and a function of the linear speed or velocity of the on-line conveyor, (2) the type of solid plant matter, as described above, and (3) physicochemical characteristics and properties, such as density, of the solid plant matter subjected to the on-line drying or cooling forced-air treatment.
To one of ordinary skill in the art, there is thus a need for, and it would be useful to have a method and device for non-invasively determining moisture content and uniformity of solid plant matter during on-line drying or cooling forced-air treatment, based on measuring temperature, humidity, and flow rate of the forced-air passing through the volume of the solid plant matter. Moreover, accurate and precise determination of moisture content and uniformity of solid plant matter during forced-air treatment would enable optimization and control of the drying or cooling forced-air treatment, thereby contributing to optimization and control of an overall manufacturing sequence for producing consumer end products containing solid plant matter raw materials.
The present invention relates to a method and device for non-invasively determining moisture content and uniformity of solid plant matter during on-line drying or cooling forced-air treatment, based on measuring multiple operating parameters including temperature, humidity, and flow rate of the forced-air passing through the volume of the moving solid plant matter.
It is therefore an object of the present invention to provide a method and device for non-invasively determining moisture content and uniformity of solid plant matter during on-line drying or cooling forced-air treatment.
It is a further object of the present invention to provide such a method and device which are based on measuring primary operating parameters of temperature, humidity, and flow rate of the forced-air passing through the volume of the solid plant matter.
It is another object of the present invention to provide such a method and device which are also based on using empirically determined measurements and data featuring secondary operating parameters of volumetric bulk material transport rate of the solid plant matter, type of the solid plant matter, and physicochemical characteristics and properties of the solid plant matter, for process correcting raw parametric values of temperature, humidity, and flow rate, of the forced-air entering and exiting the volume of the solid plant matter.
Thus, according to the present invention, there is provided a method for non-invasively determining moisture content and uniformity of solid plant matter during on-line drying or cooling forced-air treatment, comprising the steps of: (a) sensing and measuring forced-air operating parameters while forced-air enters and exits the solid plant matter, said forced-air operating parameters include temperature, humidity, and flow rate; (b) processing said forced-air operating parameters for forming forced-air parametric values, said forced-air parametric values include forced-air temperature values, forced-air humidity values, and forced-air flow rate values; (c) calculating a moisture content value of the solid plant matter from said forced-air parametric values; and (d) calculating a uniformity value of the solid plant matter from at least two said moisture content values of the solid plant matter.
According to another aspect of the present invention, there is provided a method for non-invasively determining moisture content and uniformity of solid plant matter during on-line drying or cooling forced-air treatment, comprising the steps of: (a) sensing and measuring at least one set of inlet forced-air operating parameters and at least one set of outlet forced-air operating parameters, while forced-air enters and exits the solid plant matter, each said set of said forced-air operating parameters includes temperature, humidity, and flow rate; (b) processing each said set of inlet forced-air operating parameters and each set of outlet forced-air operating parameters, for forming at least one set of inlet forced-air parametric values and at least one set of outlet forced-air parametric values; (c) calculating a moisture content value of the solid plant matter from each said set of inlet forced-air parametric values and each said set of outlet forced-air parametric values; and (d) calculating a uniformity value of the solid plant matter from at least two said moisture content values of the solid plant matter.
According to another aspect of the present invention, there is provided a method for non-invasively determining moisture content and uniformity of solid plant matter during on-line drying or cooling forced-air treatment, comprising the steps of: (a) sensing and measuring forced-air operating parameters while forced-air enters and exits the solid plant matter, said forced-air operating parameters include temperature, humidity, and flow rate; (b) generating raw forced-air parametric values from said sensed and measured forced-air operating parameters, said raw forced-air parametric values include raw forced-air temperature values, raw forced-air humidity values, and raw forced-air flow rate values; (c) process correcting said generated forced-air parametric values for forming process corrected forced-air parametric values, said process corrected forced-air parametric values include process corrected forced-air temperature values, process corrected forced-air humidity values, and process corrected forced-air flow rate values, said process correcting accounts for affects of at least one secondary operating parameter on the step of said sensing and measuring said forced-air operating parameters of temperature, humidity, and flow rate; (d) calculating a moisture content value of the solid plant matter from said process corrected forced-air parametric values; and (e) calculating a uniformity value of the solid plant matter from at least two said moisture content values of the solid plant matter.
According to another aspect of the present invention, there is provided a method for non-invasively determining moisture content and uniformity of solid plant matter during on-line drying or cooling forced-air treatment, comprising the steps of: (a) sensing and measuring forced-air operating parameters while forced-air enters and exits the solid plant matter, said forced-air operating parameters include temperature, humidity, and flow rate; (b) generating raw forced-air parametric values from said sensed and measured forced-air operating parameters, said raw forced-air parametric values include raw forced-air temperature values, raw forced-air humidity values, and raw forced-air flow rate values; (c) process correcting said generated forced-air parametric values for forming process corrected forced-air parametric values, said process corrected forced-air parametric values include process corrected forced-air temperature values, process corrected forced-air humidity values, and process corrected forced-air flow rate values, said process correcting accounts for affects of at least one secondary operating parameter on the step of said sensing and measuring said forced-air operating parameters of temperature, humidity, and flow rate; (d) calculating a moisture content value of the solid plant matter from said process corrected forced-air parametric values; and (e) calculating a uniformity value of the solid plant matter from at least two said moisture content values of the solid plant matter.
The method and device of the present invention serve as significant improvements over currently used methods and devices for determining moisture content and uniformity of solid plant matter during on-line drying or cooling forced-air treatments, by providing values of moisture content and uniformity corresponding to the entire volume of moving solid plant matter, based on accurately and reproducibly measuring and using primary and secondary operating parameters during the drying or cooling forced-air treatment. This leads to achieving high levels of optimization and control of the drying or cooling forced-air treatment, thereby contributing to optimization and control of an overall manufacturing sequence for producing consumer end products containing solid plant matter raw materials.